The present invention relates to a dynamic scattering matrix liquid crystal display and, more particularly, to a driving voltage supply circuit therefor to drive a high-speed response super twisted nematic (STN) liquid crystal with high contrast, and a matrix liquid crystal display using the driving voltage supply circuit.
The dynamic scattering matrix liquid crystal display has two spaced transparent substrates arranged opposite to each other, and there is a twisted structure liquid crystal layer disposed between those transparent substrates.
For example, one of the transparent substrates may have a plurality of data line transparent electrodes which are arranged thereon on the side of the liquid crystal layer, the data line transparent electrodes being arranged in the X direction. The other of the transparent substrates may have a plurality of scanning line transparent electrodes which are arranged thereon on the side of the liquid crystal layer, the scanning line transparent electrodes being arranged in the Y direction.
There are pixel regions at each of the crossing points between the data line transparent electrodes and the scanning line transparent electrodes, and each of the data line transparent electrodes is selectively supplied with one of two voltage levels from a data line driver circuit, while each of the scanning line transparent electrodes is selectively supplied with a select signal or a non-select signal from a scanning line driver circuit.
Further, the select signal and the non-select signal supplied to the scanning line transparent electrodes are controlled so as to convert their driving waveforms into alternating waveforms by inverting the polarity thereof. The inverting of polarity in order to avoid the generation of a defective orientation controlling layer phenomenon is well known.
In general, a liquid crystal display needs data line drivers and scanning line drivers for providing the driving waveforms as alternating waveforms, and a voltage supply circuit for these data line drivers and scanning line drivers.
The conventional voltage supply circuit, as shown in FIG. 5, has output terminals for supplying 6 levels of voltage. Thus, the conventional LCD (liquid crystal display) typically uses an amplitude-selective addressing scheme, and includes resistors and operational amplifiers. In accordance with the amplitude-selective addressing scheme, as shown in FIG. 6, voltages V2 and V4 for the data lines and voltages V1 and V5 for the scanning lines are supplied in a first cycle (e.g. a positive polarity cycle), and voltages V1 and V3 for the data lines and voltages V2 and V6 for the scanning lines are supplied in a second cycle (e.g. a negative polarity cycle).
The conventional voltage supply circuit of this type and the amplitude-selective addressing scheme are discussed in detail, for example, in U.S. Pat. No. 3,976,362 (Japanese Patent No. 1,210,988) to Kawakami.
Further, in the dynamic scattering matrix liquid crystal display, there can occur a missing mouse cursor phenomenon in which the operator may miss seeing the mouse cursor moving quickly, as a result of the difference between the driving principles of a TFT (thin film transistor) LCD representative of an active matrix LCD and the dynamic scattering matrix LCD.
Each of the transparent electrodes (ITO) disposed at the pixel regions of the active matrix LCD hold a static charge according to the voltage supplied from the data line driver for the period in which each scanning line (gate line) is not supplied with the predetermined select level voltage.
However, in the dynamic scattering matrix LCD, the display picture is determined by an effective voltage value in response to the potential difference for only a scanning period, thereby pulse driving the pixel regions at each crossing point between the data line transparent electrodes and the scanning line transparent electrodes.